After a week-long trial last July, Justice Timothy Brewer also dismissed Opai's court action against the police.
Opai has since taken Justice Brewer's judgment to the Court of Appeal.
By the end of the High Court proceedings, the employment saga had cost police some $841,590 in legal fees to defend Opai's claims, the Herald revealed with information released under the Official Information Act (OIA).
However, the Herald now understands the police's legal costs have risen further and are expected to continue to grow with Opai challenging the original substantive decision in the Employment Court.
She is also appealing the costs order which relates to the substantive decision, while other matters linked to the case are currently before the ERA.
"Sometimes we must face losing the battles, in order to win the war," Opai told the Herald today.
After the High Court dismissals, police also returned to the ERA earlier this year to seek an order for Opai to pay up.
During the ERA leg, police engaged top commercial law firm Buddle Findlay and it cost at least $186,367, according to the Herald's OIA.
Police wanted Opai to pay $15,000 towards its legal costs and said defending her claims in the ERA alone have now exceed $200,000.
It said there was significant costs associated with preparing for the two-day ERA hearing because Opai's claims were complex and detailed and she made wide-ranging and general information requests.
Opai had also requested several irrelevant documents, police claimed.
Both hearing days were longer than usual and considerable work was required, police said, to respond to evidential issues which arose from Opai's closing arguments.
Opai, however, argued she should not be ordered to pay more than $8000 in costs.
She also sought a stay of any costs order until her challenge to the Employment Court had been resolved and until her other ERA claims have been determined.
In its decision, released publicly last week, the ERA found the police should bear responsibility for some of the document issues that arose and resulted in additional time and legal costs.
"The authority also accepts that Ms Opai has very limited means by which to pay an award of costs and that there is no imminent prospect of her financial situation changing," it said.
"The award of costs in this case is likely to be a significant burden on Ms Opai. In addition she is also facing additional costs as a result of her challenge and the further as yet unheard claims which are currently before the authority."
Because of this, the ERA ordered Opai to pay $6000 to the police's legal costs, $2000 less than the usual daily tariff for a two-day investigation meeting.
But it also declined to stay the costs order pending the outcome of her Employment Court challenge.
Opai is currently without a job after her police career ended with a blunt termination letter just hours after she lost her High Court defamation case, the Herald earlier revealed.
But police have claimed it was just an unfortunate timing coincidence - despite an email obtained by the Herald showing the sender of the letter, the District Commander for Counties Manukau, was aware of the court's decision.
Opai's lawyers later received a letter from Buddle Findlay apologising for sending the termination letter within hours of the judgment.
